BERLIN — Edward J. Snowden, the fugitive American security contractor granted temporary asylum by Russia, has appealed to Washington to stop treating him like a traitor for revealing that the United States has been eavesdropping on its allies, a German politician who met with Mr. Snowden said on Friday.

Mr. Snowden made his appeal in a letter that was carried to Berlin by Hans-Christian Ströbele, a veteran member of the Green Party in the German Parliament. Mr. Ströbele said he and two journalists for German news outlets met with Mr. Snowden and a person described as his assistant — probably his British aide, Sarah Harrison — at an undisclosed location in or near Moscow on Thursday for almost three hours.

Mr. Ströbele had gone to Moscow to explore whether Mr. Snowden could or would testify before a planned parliamentary inquiry into the eavesdropping. Any arrangements for Mr. Snowden to testify would require significant legal maneuvering, as it seemed unlikely that he would travel to Germany for fear of extradition to the United States.

In his letter, Mr. Snowden, 30, also appealed for clemency. He said his disclosures about American intelligence activity at home and abroad, which he called “systematic violations of law by my government that created a moral duty to act,” have had positive effects.

Yet “my government continues to treat dissent as defection, and seeks to criminalize political speech with felony charges that provide no defense,” Mr. Snowden wrote. “However, speaking the truth is not a crime. I am confident that with the support of the international community, the government of the United States will abandon this harmful behavior.”

Mr. Ströbele, 74, is a seasoned left-wing defense lawyer and the longest-serving member of the parliamentary committee that oversees German intelligence. At a packed news conference after his return to Berlin, he said he was contacted about going to Moscow late last week after the German government said Chancellor Angela Merkel’s cellphone might have been tapped by American intelligence agents. He declined to elaborate, but said he has had no dealings with the Russian authorities or the German Embassy in Moscow.

He deftly parried requests to reveal more, while appealing to the governments and citizens of Germany, France and the United States to stop treating Mr. Snowden as a criminal.

Instead, Mr. Ströbele said, echoing an opinion gaining support here, Germany should thank Mr. Snowden. After ARD, the premier German television network, reported on Thursday night about the Moscow visit, it broadcast a commentary arguing that Germany should show gratitude for his exposure of United States intelligence practices.

Mr. Ströbele said he had found Mr. Snowden lucid and well informed. He said he had been told that Mr. Snowden was allowed to go shopping, but Mr. Ströbele declined to reveal any other details about Mr. Snowden’s routine.

News about the visit to Moscow eclipsed a number of interviews given on Thursday by the American ambassador, John B. Emerson, who tried to assuage German fears that the United States Embassy in Berlin was the center for monitoring Ms. Merkel and other well-placed Germans.

Ms. Merkel, while palpably angry in appearances last week, has made no direct statements since, quietly sending two senior advisers to Washington this week to begin re-establishing the trust she said had been breached.

Mr. Ströbele’s news conference yielded moments of humor as well. At one point, his cellphone rang. He pulled it out, looked at it and asked cheerfully, “Does anybody know the chancellor’s number?”

Asked to speculate about which intelligence services might have monitored his trip to Moscow, he said with a smile, “I assume that they are all interested.”

A version of this article appears in print on , on Page A4 of the New York edition with the headline: Snowden Asks U.S. to Stop Treating Him Like a Traitor. Order Reprints | Today’s Paper | Subscribe